(European X-ray Observatory Satellite, HELOS)
(1980s European space X-ray telescope)
EXOSAT was a 1980s space X-ray telescope
operated by the European Space Agency.
(It has no relation to exosatellites.)
It used lunar occultation observations
to add precision to its observations, having been
placed in a highly eccentric orbit to
assist in this and to reach high enough that
X-rays are unimpeded.
It carried out a slew survey, with new discoveries
designated by the prefix EXO.
Referenced by page:
European Space Agency (ESA)